In situ measurements of tropospheric volcanic plumes in Ecuador and Colombia during TC^4
Abstract
A NASA DC-8 research aircraft penetrated tropospheric gas and aerosol plumes sourced from active volcanoes in Ecuador and Colombia during the Tropical Composition, Cloud and Climate Coupling (TC^4) mission in July–August 2007. The likely source volcanoes were Tungurahua (Ecuador) and Nevado del Huila (Colombia). The TC^4 data provide rare insight into the chemistry of volcanic plumes in the tropical troposphere and permit a comparison of SO_2 column amounts measured by the Ozone Monitoring Instrument (OMI) on the Aura satellite with in situ SO_2 measurements. Elevated concentrations of SO_2, sulfate aerosol, and particles were measured by DC-8 instrumentation in volcanic outflow at altitudes of 3–6 km. Estimated plume ages range from ~2 h at Huila to ~22–48 h downwind of Ecuador. The plumes contained sulfate-rich accumulation mode particles that were variably neutralized and often highly acidic. A significant fraction of supermicron volcanic ash was evident in one plume. In-plume O_3 concentrations were ~70%–80% of ambient levels downwind of Ecuador, but data are insufficient to ascribe this to O_3 depletion via reactive halogen chemistry. The TC^4 data record rapid cloud processing of the Huila volcanic plume involving aqueous-phase oxidation of SO_2 by H_2O_2, but overall the data suggest average in-plume SO_2 to sulfate conversion rates of ~1%–2% h^(−1). SO_2 column amounts measured in the Tungurahua plume (~0.1–0.2 Dobson units) are commensurate with average SO_2 columns retrieved from OMI measurements in the volcanic outflow region in July 2007. The TC^4 data set provides further evidence of the impact of volcanic emissions on tropospheric acidity and oxidizing capacity.
Additional Information
© 2011 American Geophysical Union. Received 6 July 2010; accepted 16 February 2011; published 10 May 2011. We acknowledge NASA funding for Aura validation (contracts NNG06GJ02G and NNX09AJ40G). Mark Schoeberl spearheaded the effort to intercept the volcanic plumes during the TC4 science flights. We thank Santiago Arellano for assistance with flight planning and volcanic activity reports during the TC4 mission and Cynthia Twohy for providing CVI data. The NOAA Air Resources Laboratory is acknowledged for the provision of the HYSPLIT transport and dispersion model and READY website (http://www.arl.noaa.gov/ready.html). We thank R. S. Martin and an anonymous reviewer for thorough reviews that greatly improved the paper.Attached Files
Published - Carn2011p13961J_Geophys_Res-Atmos.pdf
Supplemental Material - 2010jd014718-fs01.tif
Supplemental Material - 2010jd014718-fs02.tif
Supplemental Material - 2010jd014718-fs03.jpg
Supplemental Material - 2010jd014718-fs04.jpg
Supplemental Material - 2010jd014718-fs05.tif
Supplemental Material - 2010jd014718-readme.txt
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Additional details
- Eprint ID
- 23825
- Resolver ID
- CaltechAUTHORS:20110527-115645829
- NASA
- NNG06GJ02G
- NASA
- NNX09AJ40G
- Created
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2011-05-31Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences